Internal combustion engines combust a mixture of fuel and air in order to produce torque to propel a vehicle. Specifically, air is drawn into the engine via an engine intake based on a position of a throttle, and then the air is mixed with fuel. The air-fuel mixture is combusted within engine cylinder(s), to drive piston(s) within the cylinder(s), thus rotating an engine crankshaft. By-products of combustion within the engine cylinders are routed to one or more catalysts via an exhaust manifold, prior to exiting to atmosphere.
Both the engine intake and exhaust systems may exhibit degradation, over time. Any presence of degradation in the intake manifold, exhaust system, or engine may lead to a decrease in fuel economy, and in some examples may lead to an increase in undesired emissions. The inventors have herein recognized these issues.
Engine operation may be regulated based on a number of parameters, such as the air flow rate provided to the engine. A measurement of air flow provided to the engine may be determined by a mass air flow (MAF) sensor, for example. However, in the intake manifold, any presence of degradation downstream of the MAF sensor may result in unmetered air being provided to the engine. As a result, the air-fuel ratio may switch lean. However, there are many other root causes for an engine running lean, such as undesired combustion, exhaust gas oxygen sensors that are not functioning as desired, valve timing issues, the MAF sensor not functioning as desired, etc. Thus, it can be challenging to specifically diagnose the presence or absence of degradation stemming from an intake system or intake manifold downstream of a MAF sensor. Similarly, degradation in the exhaust system may be difficult to pinpoint, if said degradation is downstream of an exhaust gas oxygen sensor, for example.
U.S. Patent No. US20090187301 teaches a method of diagnosing the presence or absence of degradation in an intake manifold of an engine, by comparing manifold absolute pressure to atmospheric pressure. In one example, a significant amount of degradation is indicated responsive to manifold absolute pressure being substantially equivalent to atmospheric pressure.
However, the inventors herein have recognized potential issues with such a method. For example, such a method is unable to diagnose the presence or absence of degradation in an exhaust system of the vehicle. Thus, the inventors have herein developed systems and methods to address such issues. In one example, a method is provided, comprising spinning an engine of a vehicle unfueled in a forward and a reverse direction to obtain a first intake air flow and a second intake air flow, respectively, in an intake of the engine; and indicating a source of degradation stemming from one of the engine, an intake manifold of the engine, or an exhaust system of the engine based on both the first air flow and the second air flow.
In one example, prior to spinning the engine unfueled in the forward and the reverse direction to obtain the first intake air flow and the second intake air flow, obtaining a set of baseline comparator data that includes spinning the engine unfueled in the forward and the reverse direction to obtain a first baseline intake air flow and a second baseline intake air flow; and wherein spinning the engine unfueled in the forward and the reverse direction is conducted via a motor powered by a battery.
In this way, degradation stemming from one of the engine, intake manifold of the engine, or exhaust system of the engine, may be diagnosed, based on one test diagnostic procedure. By pinpointing where in an engine system there is degradation, repairs may be streamlined, customer satisfaction may be improved, and release of undesired emissions to atmosphere may be reduced.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.